Liang Shuquan

Effects of La3+ doping on MnZn ferrite nanoscale particles synthesized by hydrothermal method

MnZn ferrite nanoscale particles were synthesized by hydrothermal method. The effects of amount of addition La3+ on the products were discussed. The product was characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The results show that the sample with 0.2% La3+ (mass fraction) or without La3+ has only spinel phase, but the sample with mass fraction of La3+ exceeding 0.4% posses second phase besides the spinel one; and the nano-MnZn ferrites change from cube to hexagon when the mass fractions of La3+ is up to 1.2%. TEM image of the sample with 1.2% La3+ indicates that the homogeneous hexagonal crystal is obtained and the particles are larger than those of undoped; the addition of La3+ has great influence on the crystallization of hydrothermal process and can change the shape of particles and improve their growth. The saturation magnetization of the sample with 1.2% La3+ (2.64 A · m2 · kg−1) is lower than that of undoped (17.54 A · m2 · kg−1) and it behaves superparamagnetically.

Rational synthesis of SnS 2 @C hollow microspheres with superior stability for lithium-ion batteries

Tin-based nanomaterials have been extensively explored as high-capacity anode materials for lithium ion batteries (LIBs). However, the large volume changes upon repeated cycling always cause the pulverization of the electrode materials. Herein, we report the fabrication of uniform SnS2@C hollow microspheres from hydrothermally prepared SnO2@C hollow microspheres by a solid-state sulfurization process. The as-prepared hollow SnS2@C microspheres with unique carbon shell, as electrodes in LIBs, exhibit high reversible capacity of 814 mA h g−1 at a current density of 100 mA g−1, good cycling performance (783 mA h g−1 for 200 cycles maintained with an average degradation rate of 0.02% per cycle) and remarkable rate capability (reversible cap-abilities of 433 mA h g−1 at 2 C). The hollow space could serve as extra space for volume expansion during the charge-discharge cycling, while the carbon shell can ensure the structural integrity of the microspheres. The preeminent electrochemical performances of the SnS2@C electrodes demonstrate their promising application as anode materials in the next-generation LIBs.摘要锡基材料作为锂离子电池高容量负极材料得到了广泛研究. 然而循环充放电过程中的大体积变化通常会造成电极材料粉化. 本文报道了水热法合成SnO2@C空心微米球, 再对其进行固相硫化制备SnS2@C空心微米球的方法. 制得的SnS2@C空心微米球具有独特的碳外壳及空心结构, 用作锂离子电池电极材料时, 在100 mA g-1电流密度下表现出814 mA h g−1的高可逆容量, 优秀的循环性能(循环200圏后仍保留783 mA h g−1, 平均每圏损失0.02%), 以及出色的倍率容量(2 C时为433 mA h g−1). 其内部空心部分可为充放电循环过程中的体积膨胀提供额外空间, 同时碳外壳能够保护微米球的完整性. 该SnS2@C出色的电化学性能展示出用于下一代锂离子电池负极材料的应用前景.

New development of Einstein’s viscose law for powder suspension systems

Through the analysis of the present situation of the rheology of suspension disperse systems, the classical Einstein’s viscosity law was developed into the generalized Einstein’s viscosity law which can be further developed into universalized form, called the universalized Einstein’s viscosity law by introducing modification function f(φ). Some rational forms of the function f(φ) were discussed according to functional approximation method, and were consequently developed into a few suspension disperse system rheological equations suitable for high particle concentration. These equations all keep good consistence with the models acquired in experiments or other mathematical physics analysis.

Effect of La, Y Additions on ZrO

借助DSC、XRD、SEM和TEM等技术探讨了La 2 O 3 、Y 2 O 3 掺杂对非晶晶化法制备ZrO 2 -mullite纳米复相陶瓷的影响。结果表明, 当Y 2 O 3 和La 2 O 3 的掺杂量分别小于4wt%和1.8wt%时, 能有效降低Si-Al-Zr-O系非晶的熔制温度, 抑制冷却过程中的失透现象, 有利于非晶形成且不影响主晶相的析出。单一Y2O3掺杂时, Y主要固溶于氧化锆中, 稳定t-ZrO 2 , 且抑制堇青石析出, 对晶粒大小影响不大; 而Y 2 O 3 和La 2 O 3 混合掺杂时, Y和La主要存在于玻璃相中, 强化晶界, 且La能明显促进ZrO2、mullite晶粒长大。Y 2 O 3 和La 2 O 3 的合适添加量分别为1.0wt%~ 2.0wt%和0.6wt%~ 1.2wt%。

lt;inf

借助DSC、XRD、SEM和TEM等技术探讨了La 2 O 3 、Y 2 O 3 掺杂对非晶晶化法制备ZrO 2 -mullite纳米复相陶瓷的影响。结果表明, 当Y 2 O 3 和La 2 O 3 的掺杂量分别小于4wt%和1.8wt%时, 能有效降低Si-Al-Zr-O系非晶的熔制温度, 抑制冷却过程中的失透现象, 有利于非晶形成且不影响主晶相的析出。单一Y2O3掺杂时, Y主要固溶于氧化锆中, 稳定t-ZrO 2 , 且抑制堇青石析出, 对晶粒大小影响不大; 而Y 2 O 3 和La 2 O 3 混合掺杂时, Y和La主要存在于玻璃相中, 强化晶界, 且La能明显促进ZrO2、mullite晶粒长大。Y 2 O 3 和La 2 O 3 的合适添加量分别为1.0wt%~ 2.0wt%和0.6wt%~ 1.2wt%。

gt;2

Abstract Effect of preaging at room temperature and at 150°C on the precipitation of the S′ phase in 8090 and 2091 type Alz.sbnd;Li alloys has been investigated. The results indicate that in the specimens naturally aged at room temperature prior to aging at 190°C, the S′ phase is preferentially nucleated and grows on dislocation loops. Preaging at 150°C also promoted S′ precipitation due to the increased driving force for precipitation. Higher Cu and Mg contents are favourable for S′ precipitation.